Powered, fastener-driving tools, of the type used to drive various fasteners, such as, for example, staples, nails, and the like, typically comprise a housing, a power source, a supply of fasteners, a trigger mechanism for initiating the firing of the tool, and a workpiece-contacting element. The workpiece-contacting element is adapted to engage or contact a workpiece, and is operatively connected to the trigger mechanism, such that when the workpiece-contacting element is in fact disposed in contact with the workpiece, and depressed or moved inwardly a predetermined amount with respect to the tool, as a result of the tool being pressed against or moved toward the workpiece a predetermined amount, the trigger mechanism will in fact be enabled so as to initiate firing of the fastener-driving tool. As is well-known in the art, powered, fastener-driving tools normally have two kinds or types of operational modes, and the tool is accordingly provided with some mechanism, such as, for example, a lever, a latch, a switch, or the like, for enabling the operator to optionally select the one of the two types or kinds of operational modes that the operator desires to use in accordance with a particularly apt mode of installing the fasteners.
More particularly, in accordance with a first one of the two types or kinds of modes of operating the powered, fastener-driving tool, known in the industry and art as the sequential or single-shot mode of operation, the depression or actuation of the trigger mechanism will not in fact initiate the firing of the tool and the driving of a fastener into the workpiece unless the workpiece-contacting element is initially depressed against the workpiece. Considered from a different point of view or perspective, in order to operate the powered, fastener-driving tool in accordance with the sequential or single-shot mode of operation, the workpiece contacting element must first be depressed against the workpiece followed by the depression or actuation of the trigger mechanism. Still further, once the particular fastener has in fact been driven into the workpiece, further or repeated depression or actuation of the trigger mechanism will not result in the subsequent driving of additional fasteners into the workpiece unless, and until, the workpiece contacting element is permitted to be effectively reset to its original position and once again disposed in contact with, and pressed against, the workpiece prior to the depression or actuation of the trigger mechanism each time the tool is to be fired so as to drive a fastener into the workpiece. Alternatively, in accordance with a second one of the two types or kinds of modes of operating the powered, fastener-driving tool, known in the industry and art as the bump-firing mode of operation, the operator initially maintains the trigger mechanism at its depressed position, and subsequently, each time the workpiece contacting element is disposed in contact with, and pressed against, the workpiece, the tool will fire, thereby driving a fastener into the workpiece.
Continuing further, trigger assemblies are known wherein mechanisms are provided upon, or incorporated within, the trigger assemblies of the fastener-driving tools for permitting the operator to optionally select the particular one of the two types or kinds of modes of operating the powered, fastener-driving tool that the operator desires to implement in order to drive fasteners into the workpiece in a predetermined manner so as to achieve predetermined fastening procedures. One such trigger assembly is disclosed, for example, within U.S. Pat. No. 6,543,664 which issued to Wolfberg on Apr. 8, 2003. In accordance with the disclosed control system of Wolfberg, and with reference being made to FIG. 1, which substantially corresponds to FIG. 3 of the noted patent to Wolfberg, the trigger assembly is disclosed at 16 and is seen to comprise a trigger 18 which includes a pair of spaced apart side walls 20 between which there is interposed a finger contact portion 22. The side walls 20 and the finger contact portion 22 effectively define an inner cavity 30 that is open at the upper end portion 32 thereof, and an actuation lever 34 is disposed within the inner cavity 30. The actuation lever 34 is pivotally mounted within the inner cavity 30 by means of an end portion 38 thereof, which comprises an eyelet or throughbore 40 within which there is disposed a pivot pin 42, and the actuation lever 34 also comprises a free distal end portion 36. An upper corner portion of each one of the side walls 20 is provided with an eyelet or throughbore 26 within which a pivot pin 28 is disposed, and in this manner, the entire trigger assembly 16 is pivotally mounted upon the tool housing 12.
It is further seen that the pair of side walls 20 are provided with a pair of notches 46,48 within which the pivotal end portion 38 of the actuation lever 34 can be selectively disposed such that the operator can operationally choose which mode of operation the fastener-driving tool will perform, that is, either the sequential firing mode of operation or the bump firing mode of operation, and it is seen still further that the fastener-driving tool also comprises a workpiece contacting element 44. As a result of the pivotal end portion 38 of the actuation lever 34 being disposed within either one of the two positions determined by means of the pair of notches 46,48, the free distal end portion 36 of the actuation lever 34 may be disposed relatively closer to, or farther from, a trigger end portion 60 of the workpiece contacting element 44. More particularly, when the actuation lever 34 is disposed relatively further away from the trigger end portion 60 of the workpiece contacting element 44, the fastener-driving tool will be disposed in its sequential firing mode of operation, whereas when the actuation lever 34 is disposed relatively closer to the trigger end portion 60 of the workpiece contacting element 44, the fastener-driving tool will be disposed in its bump-firing mode of operation. It is seen still further that the fastener-driving tool further comprises a control valve 52 which initiates firing of the fastener-driving tool, whereby a fastener is driven outwardly from the fastener-driving tool and into the workpiece, and that a coiled spring 54 circumscribes the control valve 52 so as to be interposed between the tool housing 12 and an upper surface portion 56 of the actuation lever 34. In this manner, the actuation lever 34 is effectively biased toward the finger contact portion 22 of the trigger 18 such that the pivot pin 42 of the pivotal end portion 38 of the actuation lever 34 is assuredly seated within one of the notches 46,48. It is further appreciated that the workpiece contacting element 44 comprises a plurality of linkage members 62 which effectively integrally interconnect the actual workpiece contacting member 64 with the trigger end portion 60 thereof.
In order to appreciate the achievement, for example, of the sequential firing of the fastener-driving tool, reference is made to FIGS. 1 and 2 of the drawings, which substantially correspond to FIGS. 3 and 4 of the aforenoted Wolfberg patent. More particularly, it is to be noted that in order to fire the fastener-driving tool, and thereby drive a fastener out from the fastener-driving tool and into a workpiece, the free distal end portion 36 of the actuation lever 34 must be disposed within the vicinity of the trigger end portion 60 of the workpiece contacting element 44 such that the actuation lever 34 can in fact be moved upwardly toward the control valve 52, by means of the trigger end portion 60 of the workpiece contacting element 44, when the workpiece contacting element 44 is depressed into contact with the workpiece, so as to be ready to be subsequently moved upwardly into contact with the control valve 52 by means of the finger contact portion 22 of the trigger 18 when the finger contact portion 22 of the trigger 18 is in fact depressed or moved upwardly. Accordingly, when in fact a sequential firing mode of operation of the fastener-driving tool is to be performed, the operator will dispose the workpiece contacting member 64 of the workpiece contacting element 44 into contact with the workpiece, and subsequently, the operator will effectively move the fastener-driving tool downwardly, or toward the workpiece, causing the workpiece contacting element 44 to effectively move upwardly relative to the tool housing 12. As a result of such relative upward movement of the workpiece contacting element 44, the trigger end portion 60 of the workpiece contacting element 44 will engage the free distal end portion 36 of the actuation lever 34 so as to move the actuation lever 34 upwardly toward the control valve 52.
Subsequently, when the finger contact portion 22 of the trigger 18 is depressed or moved upwardly with respect to the tool housing 12, the entire trigger assembly 16 will be pivotally moved around the pivot pin 28 such that the actuation lever 34 can now in fact contact and actuate the control valve 52 whereby firing of the fastener-driving tool, as a result of which a fastener is discharged outwardly from the fastener-driving tool and into the workpiece, occurs. It is to be additionally noted, however, that as a result of the aforenoted pivotal movement of the entire trigger assembly 16 around the pivot pin 28 in accordance with the depression or upward movement of the finger contact portion 22 of the trigger 18 relative to the tool housing 12, the free distal end portion 36 of the actuation lever 34 will also move slightly toward the right, as viewed in FIGS. 1 and 2, relative to the vertically oriented linear path of movement of the trigger end portion 60 of the workpiece contacting element 44, as can be appreciated from a comparison of the relative disposition of the free distal end portion 36 of the actuation lever 34, during both the non-actuated or non-depressed, and the actuated or depressed, states of the finger contact portion 22 of the trigger 18 as respectively illustrated within FIGS. 1 and 2.
Accordingly, if the operator maintains the finger contact portion 22 of the trigger 18 at its depressed or upwardly moved, pivotal position relative to the tool housing 12, then when the operator removes the fastener-driving tool from its contact or depressed state with respect to the workpiece, in order to, for example, move the fastener-driving tool to a new or other location, relative to the workpiece, at which another fastener is to be driven into the workpiece, the workpiece contacting element 44 will be moved downwardly, under the biasing influence of its spring-biasing means, not illustrated, such that the trigger end portion 60 of the workpiece contacting element 44 will effectively be released or disengaged from the free distal end portion 36 of the actuation lever 34. Therefore, the actuation lever 34 will, in turn, move downwardly away from the control valve 52, under the biasing influence of the coil spring 54, so as to attain the position illustrated within FIG. 2 wherein it is noted that the free distal end portion 36 of the actuation lever 34 is in fact removed from the vertically oriented linear path of movement of the trigger end portion 60 of the workpiece contacting element 44. Accordingly, if the operator then depresses the workpiece contacting element 44 into contact with the workpiece at the new location at which the next fastener is to be driven into the workpiece, the relative upward movement of the workpiece contacting element 44 will not result in the trigger end portion 60 of the workpiece contacting element 44 engaging the free distal end portion 36 of the actuation lever 34, but to the contrary, will effectively bypass the same, whereby the actuation lever 34 will not be capable of actuating the control valve 52 so as to initiate a new firing cycle within the fastener-driving tool.
It is to be additionally appreciated that this mode of operation, or failure of operation, will also occur if, subsequent to the successful firing of the fastener-driving tool, the finger contact portion 22 of the trigger 18 is in fact released back to its non-depressed state or position as illustrated within FIG. 1, the workpiece contacting element 44 is released from its depressed state or position with respect to the workpiece whereby the workpiece contacting element 44 will effectively move vertically downwardly, and prior to the disposition of the workpiece contacting element 44 in a depressed engaged state with respect to a new site of the workpiece at which a new fastener is to be driven into the workpiece, the finger contact portion 22 of the trigger 18 is again depressed or moved upwardly with respect to the tool housing 12. In other words, in accordance with the sequential firing mode of operation, the workpiece contacting element 44 must always be moved into depressed contact engagement with a portion of the workpiece prior to the depresssion or upward movement of the finger contact portion 22 of the trigger 18 with respect to the tool housing 12.
Alternatively, as can best be appreciated from FIGS. 3 and 4, which substantially correspond to FIGS. 5 and 6 of the aforenoted Wolfberg patent, when the fastener-driving tool is desired to be operated in accordance with the bump-firing mode of operation, it is noted that the actuation lever 34 is initially moved toward the left, as viewed within FIGS. 3 and 4, such that the pivotal end portion 38 of the actuation lever 34 is now disposed within the notch 46 whereby the free distal end portion 36 of the actuation lever 34 is disposed closer to the trigger end portion 60 of the workpiece contacting element 44. This movement of the actuation lever 34 may be achieved by inserting a pointed object, such as, for example, a nail, or the like, into one end of the pivot pin 42 of the pivotal end portion 38 of the actuation lever 34, the pivot pin 42 comprising a hollow tubular structure or having recessed means formed within an end portion thereof for accommodating the nail or the like. As illustrated within FIG. 5, all components are disposed at their normal static positions, that is, the workpiece contacting element 44 has not yet been depressed against the workpiece so as not to as yet have been moved upwardly with respect to the tool housing 12, and the finger contact portion 22 of the trigger 18 has likewise not as yet been depressed or moved upwardly.
Accordingly, with the component parts disposed at their relative positions illustrated within FIG. 3, if the workpiece contacting element 44 is initially depressed into contact with a workpiece and is accordingly moved upwardly with respect to the tool housing 12, and if the finger contact portion 22 of the trigger 18 is subsequently depressed or moved upwardly with respect to the tool housing 12, then the firing mode of operation is substantially the same as that previously described in connection with the sequential firing mode of operation. However, it is to be noted that once a fastener-driving tool firing and fastener driving cycle has been completed, and another fastener-driving tool firing and fastener driving cycle is to be implemented so as to discharge another fastener out from the fastener-driving tool and drive the same into the workpiece, if the finger contact portion 22 of the trigger 18 is maintained at its depressed or upward position, as illustrated within FIG. 4, and if the workpiece contacting element 44 has been removed from its depressed contact engagement state with respect to the workpiece such that the workpiece contacting element 44 has been moved downwardly relative to the tool housing 12 under the influence of its spring biasing means, not shown, as is also illustrated within FIG. 4, the free distal end portion 36 of the actuation lever 34 will still remain disposed within the vertically oriented linear path of movement of the trigger end portion 60 of the workpiece contacting element 44 due to the previously noted relative leftward disposition of the actuation lever 34 as a result of the location of the pivotal end portion 38 of the actuation lever 34 within the notch 46. Accordingly, unlike the sequential firing mode of operation, when the workpiece contacting element 44 is again disposed in a depressed state against the workpiece, the trigger end portion 60 of the workpiece contacting element 44 can once again move the actuation lever 34 into engagement with the control valve 52 so as to in fact initiate a new firing mode or cycle within the fastener-driving tool. Therefore, relatively rapid firing of the fastener-driving tool in accordance with the bump-firing mode of operation can be achieved each time the workpiece contacting element is disposed in depressed contact against a workpiece.
While it can be appreciated that the aforenoted system of Wolfberg can successfully enable the fastener-driving tool to achieve both sequential and bump-firing modes of operation by altering the disposition of the actuation lever 34 with respect to the trigger end portion 60 of the workpiece contacting element 44, it has been noted that sometimes it is difficult to manually manipulate the pivot pin 42 so as to effectively move the pivotal end portion 38 of the actuation lever 34 from one of the notches 46,48 to the other one of the notches 46,48 in order to effectively change-over or alter the firing mode of operation of the fastener-driving tool. As has been noted, in order to achieve such an alteration in the firing mode of operation of the fastener-driving tool, a nail or similarly sharp-pointed object must be inserted into at least one of the hollow or recessed ends of the pivot pin 42, and in addition, the pivotal end portion 38 of the actuation lever 34 must be disengaged from one of the notches 46,48, against the biasing force of coiled spring 54, so as to permit the pivot pin 42 to then be inserted into the other one of the notches 46,48.
A need therefore exists in the art for a new and improved fastener-driving tool which can be provided with a trigger control mechanism that can be easily actuated or manipulated to either one of two predetermined positions or states so as to permit the fastener-driving tool to be alternatively operated in accordance with bump firing or sequential firing modes of operation.